Updated: Jul 21
#32 Science in History
05 February 1974
Today in 1974, Mariner 10 sends back information about Venus’s cloud cover.
Mariner 10 was launched by NASA in November 1973 with the objective of exploring the inner planets of our solar system. The NASA designed probe became the first spacecraft to visit the planet Mercury. Notably, it was also the first time a planet’s gravity was used to get to another planet, as well as the first time that a flyby of two planets had been accomplished during a single mission .
The Mariner 10 spacecraft made its closest approach to Venus on 5th February 1974 during the first of two flybys. The spacecraft was able to make detailed observations of the thick toxic atmosphere and showed that the surface of Venus is obscured by cloud cover. It also revealed the presence of sulfuric acid clouds, which are responsible for the planet's intense greenhouse effect and extremely high surface temperature. Despite the thick clouds, Mariner 10 also made limited observations of Venus's surface features, noting large volcanic plains, highlands, and impact craters. The craft also discovered that Venus doesn’t have a global magnetic field.